Friday, June 05, 2009

By Wray Herbert

Smart kids tend on balance to do well in school. That may seem obvious, but there are a lot of exceptions to that rule. Some kids with high IQs don’t ever become academic superstars, while less gifted kids often shine. Why would this be?

Psychologists have focused on things like self-esteem and confidence—how good kids think they are—to explain these outcomes. And the assumption has always been that such psychological traits are shaped mostly by parenting—by parents’ beliefs and expectations and modeling. But surprisingly this idea had never been scientifically tested.

Until now. Behavioral geneticist Corina Greven of King’s College London and her colleagues decided to do the first rigorous analysis of the heritability of confidence—and its relationship to IQ and performance. To do so, they studied more than 3700 pairs of twins, both identical and fraternal twins, from age seven to ten. Comparing genetically identical twins to non-identical siblings allows scientists to sort out the relative contributions of genes and environment, and when they did this they came up with surprising but unmistakable findings.

Contrary of accepted wisdom, the researchers found (and report in the June issue of Psychological Science) that kids’ confidence is heavily influenced by heredity—at least as much as IQ is. Indeed, as-yet-unidentified confidence genes appear to influence school performance independent of IQ genes, with shared environment having only a negligible influence.

The fact that confidence is heritable does not mean it is unchanging, of course. Siblings share a lot of influences living in basically the same home and community, but there are always worldly influences pulling them apart. A genetic legacy of self-confidence merely opens up many possible futures.

For more insights into human nature, visit the “We’re Only Human” blog at www.psychologicalscience.org/onlyhuman. Versions of the blog also appear regularly in the magazine Scientific American Mind and on Newsweek.com.